During the next year we plan to continue our analyses of the maturation, organization and evolution of cells in the superior colliculus. Emphasis will be placed upon completing our initial studies regarding the maturation of visual corticotectal influences and extending our work on the maturation of superior collicular efferents as well. Both anatomical and physiological studies are planned. Attention will not be restricted to the visual properties of the superior colliculus, however. We plan to complete our investigations of the topographical relationship between somatic cortex and the somatic representation in the superior colliculus. Of particular interest will be the determination of which receptive field properties of colliculus cells are dependent upon this cortical input. This will set the stage for evaluation of the somatic properties which are present in superior colliculus cells at different developmental stages and which may underly the somatic orientation capabilities at these stages. As in the past, the cat will be used as our model but different species will be employed where necessary.